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    #41
    Re: Someone explain this phenomenon? Emachines monitor

    The less invasive way I use is to buy 4 CCFL case lights from e-bay. They come in nice rugged plastic enclosures so you don't break them. They're made for decoratively lighting computer cases.

    If the inverter fires up with the known good CCFLs and stays on you know you have an issue with the CCFLs shutting it down.

    How would I plug them into the inverter board? I don't have any spares to splice the right connector plugs into them.

    It could be bad solder joints from the backlight wires to the CCFL. The inverter will shut down in a few seconds if it doesn't sense current flow through all of the CCFLs.
    So why is it when I only had one pair of lights plugged in originally as a curious test, monitor powered up fine with other pair unplugged?

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      #42
      Re: Someone explain this? Emachines monitor

      Hey guys so after reading a few threads about how the PSU works to get a little better understanding and some clues on what to check, I decided to test the start up resistor and it was shorted! Desoldered it to double check and yup it's reading 0 ohms. Would this cause my problem?

      Here's a cropped pic of it's location. I'm curious, why is it covered in what looks like heat shrink? If I replace it, should I do the same?
      Attached Files
      Last edited by caphair; 12-12-2011, 03:49 PM.

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        #43
        Re: Someone explain this? Emachines monitor

        I don't *think* that's a startup resistor. If those fail they typically go open circuit anyway. I don't know what a shorted startup resistor would do but I think it would cause more problems than just random shutdowns.

        Going by the blue colour, it could be a fusable resistor (which would explain the heatshrink) - is the part designation FRxx?

        You would really need to take the heatshrink off and check the colour codes before you decide it's shorted. It may in fact supposed to be 0 Ohms.
        "Tantalum for the brave, Solid Aluminium for the wise, Wet Electrolytic for the adventurous"
        -David VanHorn

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          #44
          Re: Someone explain this? Emachines monitor

          Part designation is R135

          I removed the heatshrink and it does have a color code. Included a pic.
          Also one lead from it on the CB is linked to one lead of a transistor (Power FET?) attached to a heatsink through a jumper (drew a line to indicate this in second pic)
          Attached Files
          Last edited by caphair; 12-12-2011, 04:18 PM.

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            #45
            Re: Someone explain this? Emachines monitor

            That is an interesting code...

            Assuming it's Red-White-Silver-Gold-Green as I interpret it, that seems to imply an 0.29 Ohm resistor with 5% tolerance and the green probably some temperature coefficient or other rating.
            "Tantalum for the brave, Solid Aluminium for the wise, Wet Electrolytic for the adventurous"
            -David VanHorn

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              #46
              Re: Someone explain this? Emachines monitor

              Originally posted by caphair View Post
              Part designation is R135

              I removed the heatshrink and it does have a color code. Included a pic.
              Also one lead from it on the CB is linked to one lead of a transistor attached to a heatsink through a jumper (drew a line to indicate this in second pic)
              if first colour red then its 0.29 ohm
              if brown then 0.19 ohm
              if orange then 0.39 ohm
              your meter wont read this because its a part of ohm
              I think they call it a current sense resistor
              Last edited by trebo; 12-12-2011, 04:26 PM.

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                #47
                Re: Someone explain this? Emachines monitor

                Originally posted by trebo View Post
                if first colour red then its 0.29 ohm
                if brown then 0.19 ohm
                if orange then 0.39 ohm
                your meter wont read this because its a part of ohm
                I think they call it a current sense resistor
                Hmm so probably not shorted then?

                Comment


                  #48
                  Re: Someone explain this? Emachines monitor

                  Originally posted by caphair View Post
                  Hmm so probably not shorted then?
                  I would say that, they burn and crack open when they fail hence that covering
                  you can test it with esr meter but as I said, I would think its ok

                  Comment


                    #49
                    Re: Someone explain this phenomenon? Emachines monitor

                    If the logic board is getting power the main power supply isn't your issue.

                    Originally posted by caphair View Post
                    How would I plug them into the inverter board? I don't have any spares to splice the right connector plugs into them.
                    I'd just tack solder the leads from the case light onto the bottom of the connectors.

                    Originally posted by caphair View Post
                    So why is it when I only had one pair of lights plugged in originally as a curious test, monitor powered up fine with other pair unplugged?
                    Did you attempt this again to see if it still functions this way?

                    Based on the looks of it that inverter is of the gutless wonder bean counter make me in inverter for the lowest cost possible variety.

                    Which means the protection is probably minimal. Good inverters should never stay running with any of the backlights unplugged for more than a few seconds. It should shut down when proper current flow through a CCFL isn't detected.

                    That means that it doesn't have output current sensing. CCFLs draw more current as they age. If the inverter circuit can't sense when the current being drawn is out of the range of a healthy CCFL it supplies this excessive current which causes the inverter driver transistors to overheat and eventually fail.

                    If this is the case the semiconductors replaced may have blown again. Check the driver transistors with a DMM for shorts or opens.

                    Or the simplest solution is one of the wires broke off a CCFL pin and it's touching a metal portion of the panel and if the inverter has output short circuit protection it's shutting itself down.
                    Last edited by Krankshaft; 12-13-2011, 05:43 AM.
                    Elements of the past and the future combining to make something not quite as good as either.

                    Comment


                      #50
                      Re: Someone explain this? Emachines monitor

                      Here is an example of a no frills inverter. Its behavior when various CCFLs were disconnected were Very Interesting.
                      I think this thread describes it .
                      Whatever I do, I consider it a success, if in the end I am breathing, seeing, feeling and hearing!

                      Comment


                        #51
                        Re: Someone explain this? Emachines monitor

                        You should see the CCFL case light inverters that run off a 12V molex connector for computer case lighting.

                        No protection to speak of not even an input fuse there are plenty of websites that attest to the damage they cause inside a case when they fail and explode.
                        Elements of the past and the future combining to make something not quite as good as either.

                        Comment


                          #52
                          Re: Someone explain this? Emachines monitor

                          Went ahead and disassembled monitor to get to the CCFLs. Figured at this point I might as well check the connections and at same time gain a learning experience.

                          The connections looked pretty good and solid to the lamps, but I noticed blackened ends on a couple while the others were light grey, possible bad lamps? I included pics.
                          Attached Files

                          Comment


                            #53
                            Re: Someone explain this? Emachines monitor

                            now you got the ccfls out, plug them back in to the board and power the monitor up
                            no need to connect the screen, just the psu and video board
                            you just need to see if any dont light up, or if all ccfls light up
                            for those brief couple of seconds
                            taking care not to short anything out
                            Last edited by trebo; 12-17-2011, 02:42 PM.

                            Comment


                              #54
                              Re: Someone explain this? Emachines monitor

                              Black on the ends always indicates old lamps, which can cause problems - although the black is not as prominent as on some I removed that were lighting up pink instead of white (pink indicates they are really stuffed!)
                              "Tantalum for the brave, Solid Aluminium for the wise, Wet Electrolytic for the adventurous"
                              -David VanHorn

                              Comment


                                #55
                                Re: Someone explain this? Emachines monitor

                                Originally posted by caphair View Post
                                The connections looked pretty good and solid to the lamps, but I noticed blackened ends on a couple while the others were light grey, possible bad lamps?
                                The lamps are one thing, but don't forget about the wiring. It could be frayed internally or burnt to a crisp at the ends. The rubber ends hide that. See

                                http://s807.photobucket.com/albums/y...klight%20lamp/
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                                  #56
                                  Re: Someone explain this? Emachines monitor

                                  Originally posted by trebo View Post
                                  now you got the ccfls out, plug them back in to the board and power the monitor up
                                  no need to connect the screen, just the psu and video board
                                  you just need to see if any dont light up, or if all ccfls light up
                                  for those brief couple of seconds
                                  taking care not to short anything out
                                  Tried this and none lit up. Reassembled monitor and now that brief flash of light is gone. What happened? Also the power led now stays on 5 seconds longer. Did I fry the lamps somehow?

                                  Comment


                                    #57
                                    Re: Someone explain this? Emachines monitor

                                    Maybe you plugged them back in wrong? Make sure you plugged them in exactly the same as they were.

                                    Some inverters use each plug as power and return for 1 lamp each - BUT some inverters use some plugs to feed power to 2 lamps, using totally separate plugs for the return wires.

                                    You can tell the difference as one wire is thicker than the other - if every plug has a thick and a thin wire you should be able to plug them where ever (someone confirm this?), but if some plugs have both thick and some both thin you will need to get it right.



                                    That or retiredcaps is right, the wiring was half-broken, and you moving the lamps around finished it off completely.
                                    "Tantalum for the brave, Solid Aluminium for the wise, Wet Electrolytic for the adventurous"
                                    -David VanHorn

                                    Comment


                                      #58
                                      Re: Someone explain this? Emachines monitor

                                      Originally posted by Agent24 View Post
                                      Maybe you plugged them back in wrong? Make sure you plugged them in exactly the same as they were.

                                      Some inverters use each plug as power and return for 1 lamp each - BUT some inverters use some plugs to feed power to 2 lamps, using totally separate plugs for the return wires.

                                      You can tell the difference as one wire is thicker than the other - if every plug has a thick and a thin wire you should be able to plug them where ever (someone confirm this?), but if some plugs have both thick and some both thin you will need to get it right.



                                      That or retiredcaps is right, the wiring was half-broken, and you moving the lamps around finished it off completely.

                                      They have the one wire thick one thin. Pretty sure I plugged them in right. I used a razor to carefully reveal connection/solder and they didn't look broken at all but maybe in the tube it was bad?

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                                        #59
                                        Re: Someone explain this? Emachines monitor

                                        have you put plugs in upside down?
                                        judging by you pics those wires look good to me, no discolouration anywhere
                                        cant see how you could damage 4 tubes without any arcing smell or noise
                                        you must have done something, but I cant think what
                                        how many plugs on ccfls 2 or 4?

                                        Comment


                                          #60
                                          Re: Someone explain this? Emachines monitor

                                          Originally posted by trebo View Post
                                          have you put plugs in upside down?
                                          judging by you pics those wires look good to me, no discolouration anywhere
                                          cant see how you could damage 4 tubes without any arcing smell or noise
                                          you must have done something, but I cant think what
                                          how many plugs on ccfls 2 or 4?
                                          2 plugs (one for each ccfl) and 4 total in monitor.

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